Bill Bradley gives his support to Al Gore, but John McCain holds out on George W. Bush and says he'll be a "force for change" for GOP.

WASHINGTON -- Republican Sen. John McCain and Democrat Bill Bradley formally conceded defeat in their presidential bids Thursday, but McCain -- unlike Bradley -- indicated he will not go quietly without getting some concessions from the GOP front-runner, Texas Gov. George W. Bush.

McCain, who plans to return to the Senate, did not specify what Bush must do to win his support but said he plans to continue to be "a force for change" within the Republican Party. That suggests he wants Bush to embrace the central issues of his insurgency, such as campaign finance reform.

A gesture by Bush to embrace McCain's ideas could heal what GOP insiders say is a bitter rift between the two factions, especially among those in Congress. Rep. Lindsey Graham, R-S.C., a McCain supporter, said he has heard many House colleagues calling for a marriage of the two candidates' agendas.

In contrast to McCain, Bradley said he would strongly support the Democratic front-runner, Vice President Al Gore. But the former senator also vowed to continue speaking out on behalf of the issues he campaigned on: health care reform, gun control and campaign finance reform.

McCain and Bradley have not expressed interest in running for vice president on a ticket with their former rivals. And there is no indication that either man would be offered the No. 2 spot.

Moments after McCain's announcement, the senator reportedly received a phone call from Minnesota Gov. Jesse Ventura, who urged him to run as an independent candidate. But one McCain confidante, former Sen. Warren Rudman, said the Arizona senator has rejected a third party or independent candidacy.

It was fitting that McCain and Bradley bowed out on the same day, since their campaigns generally appealed to the same constituencies -- independents, as well as moderates in their own parties. In fact, one might have been more successful had it not been for the presence of the other.

Although they had similar appeal, McCain, the war hero who was held as a POW for 5 1/2 years in Vietnam, clearly connected with voters much better than Bradley, the former New York Knicks star. Unlike Bradley, McCain caught fire so quickly after his early February win in New Hampshire that it appeared for a brief time that he might capture the nomination over the party's anointed candidate, Bush.

By conceding, McCain and Bradley were only recognizing that they had fallen too far behind in the race for delegates to the national party conventions.

Although McCain won primaries in New Hampshire, Michigan, Connecticut, Massachusetts, Rhode Island and Vermont, he had only 235 delegates compared to Bush's 637. Bradley, who did not win a primary, had only 382 delegates compared to Gore's 992.

The names of McCain and Bradley will appear on ballots in future primaries in nearly two dozen states -- including Florida's balloting Tuesday -- and delegates elected to represent them are still nominally obligated to vote for McCain and Bradley at the conventions.

Although McCain made it clear he was conceding defeat, he said in Sedona, Ariz., that he was "suspending" his campaign. Aides said he will resume speaking out on his issues after a 10-day vacation.

Rudman, who has been in constant contact with McCain in recent days, insisted the Arizona senator has not told his advisers what concessions he is seeking from Bush. Among other things, Bush could offer him a role in the GOP convention, a voice in the writing of the party platform or the vice presidency.

McCain pledged to take his crusade for campaign reform back to the Senate, where it began. "I will keep trying to force open doors where there are walls ... be they walls of cynicism, or intolerance, or walls raised by self-interested elite who would exclude your voice from the highest councils of government," McCain said.

Some Republicans urged the GOP's 1996 standard-bearer, former Senate Majority Leader Bob Dole, to act as an intermediary between McCain and Bush. But Rudman said he knew of no such contacts between the two camps Thursday.

Despite pressure within the GOP for a reconciliation, it would not be easy for Bush to embrace campaign finance reform. Most Republican Party officials feel McCain's proposal would give a big advantage to Democrats, and Bush himself has been taking advantage of loopholes in the current law.

Bush, who was campaigning in Colorado, congratulated his former rival "for fighting the good fight." He said he had a brief telephone conversation with McCain on Thursday and intended to have a longer talk in the near future.

"There needs to be some time to settle out," Bush said.

Gore, meanwhile, praised his former rival and welcomed his support. "Bill Bradley is a good man whom I respect greatly," Gore said. "I am honored to have his support."

Bradley's melancholy press conference in West Orange, N.J., stood in contrast to the enthusiasm that surrounded his campaign last fall, when he appeared to be in far better position than McCain to upset an establishment candidate.

The odds were always long that Bradley could upset Gore, a sitting vice president with all of the powers of incumbency at his disposal. But Bradley's life story led friends to predict for years that he would one day live in the White House.

The son of a small-town Missouri banker was an All-America basketball player at Princeton, a Rhodes Scholar, a star on the two-time champion New York Knicks and a three-term U.S. senator. In Iowa and New Hampshire, some of Bradley's high school teammates showed up at campaign events to shake hands and trade old stories.

But Bradley failed to make the same connection with many voters. He was often portrayed as aloof and arrogant. It was an image that did not reflect his occasional dry asides or sometimes passionate policy pitches on the campaign trail -- but an image Gore reinforced by saying "the presidency is not an academic exercise."

Even in Thursday's final news conference, Bradley avoided introspection. He joked that he might finally tell reporters the names of his favorite books, but he would not describe what it felt like for a lifelong winner to acknowledge defeat or what he told Gore in a call Thursday.

In many ways, the Democratic race had been over since Bradley lost New Hampshire by four percentage points. McCain won New Hampshire and the media spotlight, and Bradley spent February fruitlessly trying to regain momentum.

"It gradually faded from the screen and because of the excitement about his candidacy, McCain was the person who appealed to the independents," said Jacksonville lawyer Steve Pajcic, who helped raise more than $1-million for Bradley in Florida. "I somewhat agree with people who say there really was room for only one race."

While McCain ran a more energetic campaign, his mistakes were every bit as plain as Bradley's. At first, he failed to respond to negative attacks by Bush. When he did, in South Carolina, he overdid it by comparing his Republican rival to President Bill Clinton.

McCain regained the nation's attention more than a week ago by attacking Christian conservative televangelists Pat Robertson and Jerry Falwell. But even his most ardent supporters acknowledge that he failed to make it clear he was not attacking all Christian conservatives.

In the end, McCain not only failed to appeal to most mainstream Republicans, but he also succeeded in alienating Christian conservatives, who make up an estimated one-third of all Republican voters.